M£GA THERIUM 183 negatived this supposition. It has shown that the Armadillos are in this matter the nearest relatives of Glossotherium, This result is important as tending further to confirm the close inter- relationship of all the American Edentates as contrasted with the Old-World forms—a matter which has already been emphasised. It is suggested, however, that the absence of under fur, which is so well developed in the Sloth, and the difference shown in trans- verse sections from the hair of Myrmecophaga, may he explained by difference in habitat. Glossotherium lived under conditions similar to those under which the Armadillos live to-day. Thus the outer covering of the body became alike in the two cases, the same needs supervening in both genera. Lestodon is another allied genus, which seems to possess canines. At any rate, in front of the four molars, and separated from them by a diastema, is a smallish, somewhat canine-like tooth, in both jaws. Megalonyx and its allies are sometimes placed in a distinct family, MegalonyoMdae. M~egalonyx itself had a skull very like that of j&radypus, being shorter and not so elongated as in the Mylodontidae. There is a strong tusk anteriorly, which4 is separated by a considerable space from the three molars lying behind it. 33oth pairs of limbs seem to have possessed five toes. This is a North American genus. It differs from the bulk of the American Edentates in having a complete jugal arch. Megatherium is the type of yet a third family, Megatheriidae, of the Gravigrade Edentates. This creature is familiar from the many restorations which have been built up, and from its huge bulk, little short of that of an elephant. The skull, which is small for the size of the creature, has a complete jugal arch, from, the middle of which depends a downward process as in other allied forms. The teeth grow to an extraordinary depth, and there are five of them in the upper and four in the lower jaw—on each side of course. The fore-limbs of the Megatherium are very much more slender than the enormously bulky hind-limbs, upon which and the equally massive tail the animal seems to have supported itself while tearing down branches of trees, upon whose leaves it fed. In the scapula the acromion joins the coracoid as in Brady^ws; the clavicle is large. The fore-limb is four-toed, and the hind-limb three-toed. The latter has but one clawed digit (the third, i.e. the inner).